Possible causes
- Poor roof ventilation
- Insulation blocking the eaves
- Warm, moist air rising from bathrooms and kitchens
- Non-breathable underlay on older roofs
Warning signs
- Droplets on the underside of the felt or nail tips
- Black mould on timbers
- Damp insulation across a wide area, especially in winter
Typical solutions
- Adding eaves, tile or ridge ventilation
- Clearing insulation from the eaves
- Venting extractor fans outside rather than into the loft
When to call a roofer
If damp is widespread rather than in one spot – an inspection helps tell condensation from a leak.
This is general guidance. The cause of any roof problem can only be confirmed by inspecting the roof.